Metal catalyzed preparation of polyoxyalkylene surfactants for phenolic foam stabilization

ABSTRACT

Polyoxyalkylene surfactants for cellular foams can be prepared by reacting under free radical polymerization conditions a polyoxyalkylene adduct, a cyclic nitrogenous vinyl monomer and an esterified unsaturated dibasic acid in the presence of an organic or inorganic per-compound and a metal catalyst.

This is a divisional of application Ser. No. 319,868, filed Nov. 9,1981, which is a continuation of application Ser. No. 113,841, filedJan. 21, 1980, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the preparation of novel surfactants and theirutilization in producing cellular foam materials, particularly phenolicfoams. The surfactants are prepared by reacting under free radicalpolymerization conditions a polyoxyalkylene adduct, a cyclic nitrogenousvinyl monomer and an esterified unsaturated dibasic acid in the presenceof an organic or inorganic per-compound and a metal catalyst.

2. Description of the Prior Art

Phenolic polymers have been known for decades. More recently there hasbeen increased interest in phenolic polymers which can be formed intocellular materials more commonly referred to as foams. These foams areproduced by mixing reactants in the presence of a blowing agent. See,for example, Thomas et al. U.S. Pat. No. 2,744,875 ( 1956); NelsonCanadian Pat. No. 674,181 (1963); Dijkstra Canadian Pat. No. 684,388(1964); Wissenfels et al. Canadian Pat. No. 866,876 (1971); UnitedKingdom specification No. 598,642 (1948); Australian Pat. No. 128,508(1945); and Modern Plastics Encylopedia, Volume 41, pages 362,363(1964). However, most known cellular materials produced from phenolicpolymers exhibit an unsatisfactory thermal conductivity initially. Otherknown cellular materials produced from phenolic polymers exhibit anundesirable increase in thermal conductivity with time.

U.S. Pat. No. 4,140,842 (1979) discloses improved phenolic foammaterials made with phenol:o-cresol resoles, which are characterized byhigh thermal resistance and a relatively slow increase in thermalconductivity with time. These foams are produced utilizing a cellstabilizing surfactant which is the capped reaction product of analkoxylated amine and a copolymerizable mixture of dialkyl maleate andN-vinyl-2-pyrrolidinone or N-vinyl caprolactam. The latter co-monomersare polymerized with a combination of the initiatorsazobisisobutyronitrile and t-butyl-perbenzoate. A disadvantage of thesephenolic foams is that at higher phenol:o-cresol ratios, i.e., adeficiency of o-cresol, the cellular material produced tends to becomecoarse celled and too friable.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide a novelclass of surfactants for use in preparing fine, closed-cell foammaterials, particularly phenolic foams, and a method of producing thesurfactants, as well as a method of producing the foams by use of thesurfactants.

It is another object of the present invention to provide an improvedclosed cell phenolic-resin foam material substantially free of thedisadvantages of prior foams and an improved laminated building panelemploying the foam material.

It is still another object of the present invention to produce a closedcell phenolic-resin foam material with high thermal resistance and highinsulation properties and a relatively slow increase in thermalconductivity with time.

It is a further object of the present invention to produce aphenolic-resin foam material which exhibits a high closed cell contentwithout adversely affecting friability, compressive strength and the lowflammability characteristics of the material.

It is a still further object of the present invention to provide aclosed cell phenolic-resin foam material which can be used in buildingpanels which are highly insulating, thermally resistant, low infriability, soundproof and self-supporting.

These and other objects and advantages of the present invention willbecome more apparent by reference to the following detailed descriptionand drawings wherein:

FIG. I is a cross-sectional view of a laminated building panel havingone facing sheet; and

FIG. II is a cross-sectional view of a laminated building panel havingtwo facing sheets.

DESCRIPTION OF THE INVENTION

The above objects have been achieved and the drawbacks of the prior arthave been overcome by the development of an improved surfactant for foammaterials particularly phenolic foams, which is the product of a metalcatalyzed, free-radical initiated copolymerization of (a) a cyclicnitrogenous vinyl monomer and (b) an esterified unsaturated dibasic acidin the presence of a polyoxyalkylene adduct.

More particularly, the foam surfactant of the present inventioncomprises the reaction product of a metal catalyzed, free-radicalinitiated copolymerization of (a) a cyclic nitrogenous monomer havingthe formula ##STR1## wherein n is 3, 4, or 5, and (b) an esterifiedunsaturated dibasic acid containing 4 or 5 carbon atoms in the acidportion conducted in the presence of a polyoxyalkylene adduct. In anadvantageous embodiment of the invention, the copolymerization of thecyclic nitrogenous vinyl monomer and the esterified unsaturated dibasicacid is catalyzed by a redox system, consisting of a per-compound,preferably an organic peroxidic compound, used in conjunction with aredox metal catalyst(s), preferably a transition metal compound(s).

In the broadest aspects of the present invention, the polymerization ofthe cyclic nitrogenous vinyl monomer and esterified unsaturated dibasicacid can be conducted in the presence of any conventionalpolyoxyalkylene adduct. The polyoxyalkylene adduct can be represented bythe structural formula

    H--polyoxyalkylene chain).sub.t R,                         (II)

wherein R is an organic or inorganic radical and t is the number ofpolyoxyalkylene chains reacted onto the R backbone. Preferably, R is anorganic radical selected from aromatic, aliphatic, cycloaliphatic, andheterocyclic radicals, and combinations of these, and t is an integerfrom 1 to 50, more preferably 1 to 8, most preferably 1 to 4. Includedamong the conventional polyoxyalkylene adducts which can be employed asstarting materials are anionic, cationic and nonionic type surfactants.These surfactants may be used either alone or in admixture with eachother. Non-ionic type surfactants are preferred.

Among the conventional polyoxyalkylene adducts which can be employed arethe alkylene oxide adducts of:

(a) Mono- and polyhydroxyalkanes and mono- and polyhydroxycycloalkanes;

(b) Alkanolamines;

(c) Mono- and polyamines;

(d) Non-reducing sugars and sugar derivatives;

(e) Aromatic amine/phenol/aldehyde condensation products;

(f) Phosphorus and polyphosphorus acids;

(g) Mono- and polyhydric phenols;

(h) Amides;

(i) Organic carboxylic acids;

(j) Hydroxyl containing triglycerides;

(k) Polysiloxanes; and the like.

The adducts are prepared in known manner. Preferably, the alkyleneoxides employed in the adduct formation have 2 to 4 carbon atoms, forexample, ethylene oxide, 1,2-epoxypropane, the epoxybutanes, andmixtures thereof. Mixed propylene oxideethylene oxide adducts haveproved especially useful. In the preparation of the latter adducts, theethylene oxide and propylene oxide are advantageously reacted in themolar ratio of 10:90 to 90:10.

It has been found that the molecular weight and alkylene oxide contentof the conventional polyoxyalkylene adducts can play an important rolein determining the cell stabilizing capacity of the surfactants of theinvention. More specifically, certain adducts have been found to requirea minimum ethylene oxide content and molecular weight for more efficientcell stabilization. These requirements can vary for differentpolyoxyalkylene adducts and foam systems but it is possible to establishthe satisfactory values for any given foam through routineexperimentation.

Advantageously, the mono- and polyhydroxyalkanes and mono- andpolyhydroxycycloalkanes to be alkoxylated for use in the presentinvention can have from 1 to 8 hydroxyl groups. Illustrative alcoholsfor alkoxylation include, among others, ethylene glycol, propyleneglycol, 1,3-dihydroxypropane, 1,3-dihydroxybutane, 1,4-dihydroxybutane,1,4-, 1,5-, and 1,6-dihydroxyhexane, 1,2- 1,3-, 1,4-, 1,6- and1,8-dihydroxyoctane, 1,10-dihydroxydecane, glycerol,1,2,4-trihydroxybutane, 1,2,6-trihydroxyhexane, 1,1,1-trimethylolethane,1,1,1-trimethylolpropane, pentaerythritol, xylitol, arabitol, sorbitol,mannitol, 3,4-dihydroxycyclopentane, tetramethylolcyclohexanol,cyclohexanediol, fatty alcohols, high molecular weight polyoxyalkyleneglycols; and the like.

Another useful class of polyoxyalkylene adducts which can be employedare the alkylene oxide adducts of alkanolamines. Illustrativealkanolamines include ethanolamine, diethanolamine, triethanolamine,triisopropanolamine, and tributanolamine.

Another useful class of polyoxyalkylene adducts which can be employedare the alkylene oxide adducts of mono- and polyamines. Mono- andpolyamines suitable for reaction with alkylene oxides include, amongothers, methylamine, ethylamine, isopropylamine, butylamine,benzylamine, aniline, the toluidines, naphthylamines, ethylenediamine,diethylene triamine, triethylenetetramine, 4,4'-methylenedianiline,1,3-butanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-, 1,3-,1,4-, 1,5- and 1,6-hexanediamine, phenylenediamines, toluenediamine,naphthalenediamines, and the like.

A further class of polyoxyalkylene adducts which can be employed are thealkylene oxide adducts of the nonreducing sugars and the nonreducingsugar derivatives. Among the nonreducing sugars and sugar derivativescontemplated are sucrose, alkyl glycosides such as methyl glucoside,ethyl glucoside, and the like, glycol glycosides such as ethylene glycolglucoside, propylene glycol glucoside, glycerol glucoside, and the like.

A still further useful class of polyoxyalkylene adducts are the alkyleneoxide adducts of mono- and polyhydric phenols, including mononucleardihydroxy benzenes, higher alkyl phenols, and polyphenols. Among thephenols which can be used are found, for example, catechol, resorcinol,orcinol, nonylphenol, bisphenol A, bisphenol F, condensation products ofphenol and formaldehyde, more particularly the novolac resins,condensation products of various phenolic compounds and acrolein, thesimplest members of this class being the 1,2,3-tris(hydroxyphenyl)propanes, condensation products of various phenolic compounds andglyoxal, glutaraldehyde, and other dialdehydes, the simplest members ofthis class being the 1,1,2,2-tetrakis(hydroxyphenyl) ethanes, and thelike.

Another desirable class of polyoxyalkylene adducts are the alkyleneoxide adducts of aromatic amine/phenol/aldehyde condensation products.The condensation products are prepared by condensing an aromatic amine,for instance, aniline, toluidine, or the like, a phenol such as phenol,cresol, or the like, and an aldehyde, preferably formaldehyde, atelevated temperatures in the range of, for example, from 60° C. to 180°C. The condensation product is then recovered and reacted with alkyleneoxide, using a basic catalyst (e.g., potassium hydroxide) if desired, toproduce the adducts.

The alkylene oxide adducts of phosphorus and polyphosphorus acids areanother useful class of polyoxyalkylene adducts. Phosphoric acid,phosphorous acid, the polyphosphoric acids such as tripolyphosphoricacid, the polymetaphosphoric acids, and the like are desirable for usein this connection.

Examples of commercially available polyoxyalkylene adducts for use inthe present invention include Polyglycol 15-200 from Dow ChemicalCompany, Flo Mo 36 C and 5D from Sellers Chemical Corporation,ethoxylated sorbitan esters from Imperial Chemical Industries andPluronics from BASF Wyandotte Corporation.

Cyclic nitrogenous monomers which can be employed in the preparation ofthe cell stabilizers of the present invention areN-vinyl-2-pyrrolidinone, N-vinyl-2-caprolactam and N-vinyl-2-piperidone,preferably N-vinyl-2-pyrrolidinone.

In an advantageous embodiment of the invention, the ester of theunsaturated dibasic acid used in preparing the cell stabilizers of thisinvention corresponds to the formula:

    C.sub.u H.sub.2u-2 (CO.sub.2 C.sub.v H.sub.2v+1).sub.2     (III)

wherein

u is 2 or 3 and

v is an integer from 3 to 18, more preferably 3 to 6.

Typical examples of the esters that may be used include dibutylfumarate, dibutyl maleate, dihexyl fumarate, diamyl methylenemalonate,dipropyl itaconate, dibutyl itaconate, dimethylamyl maleate, diisooctylmaleate, dipentyl maleate, dihexyl maleate, dioctyl maleate, andditridecyl maleate, preferably dibutyl maleate.

Among the per-compounds which may be used in the free radical initiatedcopolymerization of the cyclic nitrogenous vinyl monomer and ester arethose inorganic per-compounds which are customarily employed in redoxcatalyst systems, such as hydrogen peroxide; alkali metal persulfatessuch as sodium persulfate, potassium persulfate, ammonium persulfate;alkali metal perborates; as well as organic per-compounds, particularlyorganic peroxides and hydroperoxides, such as tertiarybutyl perbenzoate,tertiary-butyl hydroperoxide, cumene hydroperoxide, di-tertiary-butylperoxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, and2,4-dichlorobenzoyl peroxide. The efficiency of the per-compounds isconditioned upon their being sufficiently active under thepolymerization conditions employed. The per-compounds are utilized inamounts sufficient to initiate the free radical polymerization of theinvention. Particular conditions affecting their efficiency are thecopolymerization temperature (in the range from about 30° to about 140°C.), and the nature of the specific metal catalyst(s) present and theadduct(s) being modified. For example, the solubility of the metalcatalyst and/or the per-compound in the copolymerization medium caninfluence the surfactant preparation. A limited solubility of aparticular metal catalyst and/or per-compound in a given reactionmixture may rule out use of the substance(s) in that mixture. It hasalso been found that use of an azo initiator such asazobisisobutyronitrile in the copolymerization reaction of the inventioncan have a detrimental effect on the stabilizing capacity of thecopolymerization product.

In the broadest aspects of the present invention, the nitrogenousmonomer/ester/polyoxyalkylene adduct polymerization may be conducted inthe presence of any metal which can interact with the per-compound freeradical initiator so as to produce a cell stabilizing surfactant of theinvention. For example, suitable metals may be selected from those knownto be capable of shortening the half-lives of free radical initiators.The metal compounds are utilized in catalytically effective amounts.Excellent catalytic properties are found to be possessed by transitionmetal compounds, especially those wherein the metal is a transitionmetal having an atomic number of 21 to 30, as e.g., compounds of iron,manganese, cobalt, copper, vanadium, etc. Both inorganic and organicmetal salts and organometallics have been found to be effective. Thefree radical polymerization can be conducted utilizing metals in singleoxidation states, as well as metals in combinations of two differentoxidation states.

Examples of useful metal catalysts having a single oxidation state arecopper (II) acetylacetonate, iron (II) acetylacetonate, iron (III)acetylacetonate, and the like. Examples of mixtures of metal catalystsof different oxidation states for use in the copolymerization of theinvention are iron (II) sulfate and iron (III) sulfate; iron (II)sulfate and iron (III) chloride; manganese (II) acetylacetonate andmanganese (III) acetylacetonate; cobalt (II) benzoate and cobalt (III)acetylacetonate; copper (I) acetate and copper (II) acetylacetonate;vanadium (III) acetylacetonate and vanadium (IV) oxide acetylacetonate;and the like.

Especially advantageous organometallic compounds for use as catalysts inpreparing the cell stabilizing surfactants of this invention areferrocenes and their analogs such as ferrocene, acetylferrocene,benzoylferrocene, cobaltocene, 1,1'-diacetylferrocene,1,1'-ferrocenebis-(diphenylphosphine), nickelocene, hafnocenedichloride, and ferrocenecarboxaldehyde. Ferrocene is preferred.

Surfactants having outstanding cell stabilizing properties are obtainedfrom a free radical copolymerization wherein a combination of ferroceneand tert.-butyl perbenzoate is utilized.

The free radical initiated copolymerization of this invention can beconducted under known polymerization conditions, using, e.g., solution,bulk, emulsion, or suspension polymerization techniques. Bulkpolymerization has been found especially useful.

The free radical copolymerization is advantageously carried out bymixing the reactants, metal catalyst(s) and initiator(s) at temperaturesfrom about 30° to about 140° C. under an inert atmosphere such as thatprovided by nitrogen and like inert gases until polymerization iscomplete. Polymerization is continued until the monomers are consumed,as detected by conventional analytical methods, such as gel permeationchromatography. Polymerization times of 1 or more hours can be expected.

The initiator(s) and metal catalyst(s) can be added at the beginning ofthe polymerization or can be added portionwise at intervals during thecourse of polymerization. Similarly, the polyoxyalkylene adduct, cyclicnitrogenous vinyl monomer and esterified unsaturated dibasic acid can bebrought together at the beginning of the polymerization or can becombined in increments as polymerization proceeds, such as by thegradual and simultaneous addition of each of the monomers to a resinkettle containing the adduct. It has been found disadvantageous to carryout a homopolymerization of the nitrogenous monomer to the adduct.

In a preferred embodiment of the invention the cyclic nitrogenous vinylmonomer and unsaturated diester monomer together constitute betweenabout 5 and 40, more preferably 15 and 25, weight percent of thecopolymerization reaction mixture. The cyclic nitrogenous vinyl monomerand unsaturated diester together comprise about 20 weight percent of thecopolymerization reaction mixture in a most advantageous and preferredembodiment of the invention. The preferred molar ratio of cyclicnitrogenous vinyl monomer to unsaturated diester in the reaction mixtureis 1:1. The concentration of per-compound initiator(s) in the mixture isadvantageously within the range of about 2 to 30 weight percent,preferably 4 to 25 weight percent, based on the total weight ofmonomers. Generally, the metal catalyst(s) is utilized at a level of0.001 to 0.1 grams per gram of initiator. Preferably, 0.001 to 0.06grams of metal catalyst(s) per gram of initiator are used.

The molecular weight of the conventional polyoxyalkylene adduct to becopolymerized can vary over a wide range. However, if the molecularweight is too low, the foam prepared with the subsequently preparedcopolymerization product gives coarse cells. No comparable limitationhas been found in the case of conventional polyoxyalkylene adducts ofhigh molecular weights. The latter adducts can be utilized in thehighest molecular weights currently available to yield fine-celled foamsin accordance with the present invention. As previously indicated, thesuitable molecular weight and alkylene oxide content for any particularadduct and foam system is readily determinable by those skilled in theart. In general, the starting material alkoxylated adduct will have amolecular weight of above about 1000, and advantageously in the range ofapproximately 2000 to 12,000. The molecular weight can be determinedfrom the equation: ##EQU1## where M.W.=molecular weight of thepolyoxyalkylene adduct

f=functionality, that is, average number of hydroxyl groups per moleculeof polyoxyalkylene adduct

OH=hydroxyl number of the polyoxyalkylene adduct.

It is desirable that the conventional polyoxyalkylene adduct used in thepresent invention be treated with a suitable agent to cap its hydroxylgroups. Suitable capping agents are those organic compounds capable ofreacting with compounds containing active hydrogen groups, such ashydroxyl groups, as determined by the Zerewitinoff method. The cappingagents convert the hydroxyl groups of the polyoxyalkylene adduct togroups which are substantially chemically inert in the cellularfoam-forming mixtures of the invention. The capping reaction takes placeunder conditions well known in the art; as, for example, described inSandler, S. R. and Karow, "Organic Functional Group Preparations,"Organic Chemistry, A Series of Monographs Edited by A. J. Blomquist,Academic Press, New York and London, 1968 Edition, pages 246-247, 1971Edition, Vol. II, page 223 and 1972 Edition, Vol. III, page 13, thedescriptions of which are incorporated herein by reference. The cappingtreatment may take place either before or after the copolymerization.Suitable capping agents include organic acids, acid anhydrides, acidchlorides, and acyloxy chlorides, such as a lower alkyl monocarboxylicacid having 1 to 10 carbon atoms selected from the group consisting ofacetic acid, propionic acid, butyric acid, hexanoic acid, octanoic acid,decanoic acid, isomers of these acids, anhydrides of these acids, acidchloride derivatives of these acids and mixtures thereof. Aceticanhydride is readily obtainable and convenient to use. Similarly,aromatic acids, anhydrides and chlorides can be employed. Benzoylchloride and substituted products of it such as 3,5-dinitrobenzoylchloride are examples of these. Alkyl and aromatic isocyanates can alsobe employed. Other factors, such as solubility in the polyoxyalkyleneadduct being treated and the solubility of the capped and metalcatalyzed surfactant in whatever resin system is to be stabilized, areconsiderations of which a practitioner in the art is cognizant inselecting the capping system which will yield the desired closed cellstabilized foam. Examples of suitable capping agents are acetic acid,acetic anhydride, acetyl chloride and 3,5-dinitrobenzoyl chloride. Thepreferred capping agent is acetic anhydride. The capping treatment istypically performed at temperatures ranging from 50° to 140° C. and isadvantageously carried out until the surfactant has a hydroxyl value ofless than 50, and preferably less than 10. The hydroxyl number isdetermined by the ASTM-D 1638 test.

One of the preferred surfactants produced by the metal catalyzed processof the present invention is the capped reaction product of analkoxylated amine having the formula: ##STR2## wherein R¹ isindependently an alkoxylated chain having the formula: ##STR3## s is aninteger from 2 to 10 inclusive and the ratio p:q is from 10:90 to 90:10,which amine has been reacted with a copolymerizable mixture of dialkylmaleate and a member selected from the group consisting of N-vinylpyrrolidinone and N-vinyl caprolactam, the alkyl of the maleate having 3to 18 carbon atoms. The preferred dialkyl maleate is dibutyl maleate.

The alkoxylation is carried out in a known manner using a mixture ofethylene oxide and propylene oxide in the molar ratio of 10:90 to 90:10and preferably from 40:60 to 60:40. The molecular weight of thealkoxylated amine is from 1500 to 12,000 and preferably from 2500 to6000. If the molecular weight of the alkoxylated amine is less than1500, foam collapse can occur. The viscosity of an alkoxylated amine ofmolecular weight higher than 6000 can prove too great for the foamsystem to be practical.

The preferred molar ratio of dibutyl maleate and N-vinyl-2-pyrrolidinoneto be reacted with the above alkoxylated amine of formula IV is 1:1, themixture of dibutyl maleate and N-vinyl-2-pyrrolidinone comprisingbetween 5 and 40 weight percent of the reaction mixture, and preferably20 weight percent of the reaction mixture. N-vinyl-2-pyrrolidinone andN-vinyl caprolactam are interchangeable in equivalent quantities, butN-vinyl-2-pyrrolidinone is preferred. The alkoxylated amine/dibutylmaleate/N-vinyl-2-pyrrolidinone reaction product is capped by reactingit with acetic anhydride.

Instead of employing branched polyols, such as the alkoxylated amine offormula IV above, as the polyoxyalkylene adduct of the invention, linearpolyols may advantageously be used. Examples of such adducts are thelinear polyols based on propanediols, supplied under the name"Pluronics" by BASF Wyandotte Corporation. Pluronic polyols are blockcopolymers of ethylene oxide and propylene oxide. One type of Pluronicsconsists of a central block of propylene oxide units with ethylene oxideblocks on each end. For any particular polyol series of this type,propylene oxide is added to 1,2-propanediol to attain a desired chainlength and then various levels of ethylene oxide are added to achievethe desired ethylene oxide: propylene oxide ratio. Another type ofPluronic are the Pluronic R series of polyols wherein ethylene oxide isfirst polymerized onto 1,3-propanediol, followed by the polymerizationof propylene oxide onto the resulting ethoxylated structure. Thealkoxylation of the Pluronics is carried out in a known manner. Phenolicfoams of excellent quality can be made by employing metal catalyzedsurfactants from Pluronics having molecular weights of 2000 or more andethylene oxide contents of 30 weight percent or above, particularlywithin the range of from 30 to 80 weight percent. No upper limit in thepolyol molecular weight has been observed for the Pluronics in thepresent invention.

The metal catalyzed copolymerization of the invention is capable ofproducing cellular foam stabilizing surfactants. By cellular foamstabilizing surfactants are meant those which keep the foam fromcollapsing and rupturing. Surfactants obtained from the metal catalyzedcopolymerization of the invention are found to be especially useful cellstabilizers in phenolic foams. They have the capability of givingfine-celled, low k-factor foams even in those phenolic foams of U.S.Pat. No. 4,140,842 which contain a relatively high phenol:o-cresolratio. The enhanced cell stabilizing efficiency of these surfactants isbelieved to be attributable to the activity of the metal catalyst(s) inincreasing the number of monomer units which copolymerize onto thepolyoxyalkylene adduct over the number added in the uncatalyzedcopolymerization. Although it appears that the role of the metal may beto catalyze perester decomposition, the metal may play other functions,as, e.g., activating the monomer double bonds or inhibiting theformation of undesired side products.

The metal catalyzed surfactants of the present invention can be utilizeddirectly in the production of fine-celled phenolic foams having highphenol:o-cresol ratios without subjecting the surfactants to theadditional separation procedures disclosed in applicant's U.S. Pat. No.4,412,014 (1983). The disclosure of this patent is incorporated hereinby reference. While metal catalyzed reaction products of the presentinvention display an exceptional phenolic foam stabilizing capacitywithout the need for any special isolation step, the same separationtechniques described in applicant's patent can be applied to these metalcatalyzed surfactants with the result that a major, phenolic foam cellstabilizing component is again isolated. However, a greater amount ofthis major component is obtained by performing the separation step onthe metal catalyzed reaction product than on the uncatalyzed one.Analysis of the metal catalyzed copolymerization reaction productreveals that its major component essentially comprises a product formedfrom the reaction of the cyclic nitrogenous vinyl monomer andunsaturated diester onto the polyoxyalkylene adduct. Isolation of thismajor component from the reaction mixture can be accomplished utilizingvarious conventional separation techniques such as fractionalprecipitation, selective extraction, and selective precipitation.Chromatography and ultracentrifugation can also be very useful.

One such separation method consists in a solvent extraction of the minorcomponent from the bulk of the product mixture. The copolymerizationreaction product is mixed with a solvent for said minor component, themixture preferably being heated, and the solvent layer is thereafterseparated from the resultant insoluble residue, as by decantation of thesolvent layer after settling of the mixture. Typically, theconcentration of the copolymerization reaction product in the solventwashing medium is from 5% to 25% by weight. The insoluble residue, afterremoval of small amounts of solvent (e.g., by evaporation), yields apurified surfactant having exceptional phenolic foam stabilizingproperties. The solvent washing can be performed in a single step or canbe repeated until little or no soluble material is extracted from theinsoluble residue, with each solvent treatment typically lasting lessthan an hour.

Any solvent can be employed in the solvent extraction which willselectively dissolve away all components of the copolymerizationreaction product except for its major component. A slight solubility ofthe major component in the extracting solvent does not seriously impairthe overall extraction process. It is, of course, understood that inpractice the remaining, non-phenolic foam stabilizing components wouldalso be utilized. One use found for these components is as cellstabilizing surfactants in isocyanurate-containing foams and urethanefoams. The solvent extraction can alternately be carried out byemploying a suitable solvent which selectively dissolves away thephenolic foam stabilizing portion from the remainder of the productmixture.

A preferred class of solvents for dissolving away the minor componentsof the copolymerization reaction product are low-boiling point liquids,such as hydrocarbons, halogenated hydrocarbons, or mixtures thereof.Suitable low-boiling liquids are those having boiling points in therange of about 35° to 80° C. The solvent extraction is convenientlycarried out at the boiling point of the solvent. Examples of solventswhich can be used are hexane, n-butyl chloride, pentane, mixed hexanes,heptane, cyclohexane, etc.

It has further been discovered that improved phenolic foam surfactantscan be prepared by another method which does not require the addition ofa metal catalyst to the above-described copolymerization reactants. Inaccordance with this further method, the cyclic nitrogenous vinylmonomer, esterified unsaturated dibasic acid monomer and polyoxyalkyleneadduct are reacted together under free radical polymerization conditionsin the presence of a conventional free-radical peroxidic initiator(s)which is used in a greater than customary amount. The use of thisincreased initiator concentration unexpectedly results in the productionof a surfactant which can satisfactorily stabilize the phenolic foams ofU.S. Pat. No. 4,140,842 having a relatively high phenol: o-cresol ratio.Examples of free-radical initiators for use in this process are organicperoxides and hydroperoxides, such as tertiary-butyl perbenzoate,tertiary-butyl hydroperoxide, cumene hydroperoxide, di-tertiarybutylperoxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, and2,4-dichlorobenzoyl peroxide, preferably tertiarybutyl perbenzoate. Azoinitiators, such as azobisisobutyronitrile, whether used alone or incombination with peresters, result in the formation of surfactants notcapable of giving fine-celled foams in high phenolic content resins.Presumably, the azo initiators do not promote the reaction of the vinylmonomers with the adduct.

Except for the higher than normal initiator level, this free radicalcopolymerization can be conducted under known polymerization conditionsand all the process conditions described above for the metal catalyzedcopolymerization of the invention are also applicable to it with theexception of the initiator level and the presence of a metal catalyst.The initiator is advantageously used in an amount greater than 2% byweight, preferably within the range of from 4% to 25% by weight (e.g.,10 to 14 weight percent), based on the total weight of the monomers.Very high initiator levels, as e.g., 12 weight percent or higher (basedon the weight of the monomers) may be used to advantage in this process.Although the surfactants prepared using a high concentration of aperester such as tertiary-butyl perbenzoate are generally satisfactoryfor all phenolic foams, the addition of a metal catalyst to the peresterwill form an even more efficient surfactant.

The surfactant, whether obtained directly from the metal catalyzedcopolymerization or from the copolymerization conducted in the presenceof a high initiator level or after a subsequent separation process, isemployed in a cell stabilizing amount in the foam-forming composition ofthe invention. Generally, the surfactant comprises from 0.05 to 10, andpreferably comprises from 0.1 to 6, weight percent of the composition.Too little surfactant fails to stabilize the foam and too muchsurfactant is wasteful. Those surfactants which are branched, non-ionic,and capped are particularly good cell stabilizers.

The metal catalyzed surfactant of the present invention is particularlyuseful in the production of a closed-cell cellular compositioncomprising a phenolic resin and blowing agent in addition to thesurfactant. Phenolic resin foams are a well-known class, phenol-aldehyderesin foams being representative and proportions of blowing agent andcatalyst components being well known in the art.

Foams of low friability can be obtained by using a preferred phenolicpolymer described in Moss U.S. Pat. No. 3,876,620. The preferredphenolic polymer is an alkylol group containing phenolic polymer of theformula: ##STR4## wherein R² is ##STR5## hydrogen or a radical of theformula: ##STR6##

The R³ 's are independently selected from the group consisting of loweralkyl, preferably of 1 to 4 carbon atoms, phenyl, benzyl, halo,preferably chloro, bromo, or fluoro, nitro, and hydrogen. The R⁴ 's areindependently selected from the group consisting of ##STR7## hydrogen,or a radical of above Formula VII.

The R⁵ 's are independently selected from the group consisting of loweralkyl, preferably of 1 to 4 carbon atoms, hydrogen, phenyl, benzyl, orfuryl. By furyl is meant the radical introduced by the use of furfural.In above Formula VI, x is an integer from 2 to 10 inclusive and ispreferably an integer from 2 to 6 inclusive. When x is less than 2, afoam produced from such a phenolic polymer tends to have too high afriability. On the other hand, as x exceeds 10, the viscosity of thepolymer increases to the point where it is difficult to process thefoam. The phenolic polymers of the present invention generally have amolecular weight between 200 and 2,000 and preferably have a molecularweight between 300 and 1,500. At lower molecular weights, the resultantfoams tend to have too high a friability, whereas at high molecularweights the viscosity of the phenolic polymer, even when a solvent ispresent, tends to be too high to permit processing.

A preferred subclass of phenolic polymers are those of the formula:##STR8## wherein R² is HOCH₂ --, hydrogen or a radical of the formula:##STR9##

The R⁴ 's in above Formulas VIII and IX are independently selected fromthe group consisting of HOCH₂ --, hydrogen or a radical of above FormulaIX.

In a preferred embodiment of the present invention, at least one of theR⁴ 's is methylol, i.e., HOCH₂ --. This is to ensure that there will becross-linking sites on the phenolic polymer. Of course, it is well knownin the art that such methylol groups or, when the aldehyde is other thanformaldehyde, alkylol groups, are automatically introduced into thepolymer by the process described below.

In the broadest aspects of the present invention, the phenolic polymercan contain widely varying ratios of the radicals of Formula VII or IXto ortho-cresol units. However, this ratio is generally from 1:3 to 10:1and is preferably from 1:1 to 4:1. At higher ratios, i.e., a deficiencyof orthocresol, the cellular material produced from such a phenolicpolymer tends to be too friable. In determining the above ratios, onemust include the radicals of Formula VII or IX present in Formula VI orVIII, respectively. The phenolic polymers of the invention can besynthesized by the methods described in U.S. Pat. No. 3,876,620, theteachings of which are incorporated herein by reference.

The phenolic compositions useful in the present invention generallycomprise the phenolic polymer of Formula VI or Formula VIII, togetherwith a compound of the formula: ##STR10## wherein the R³ 's areindependently selected from the group consisting of lower alkyl,preferably of 1 to 4 carbon atoms, phenyl, benzyl, halo, preferablychloro, bromo, or fluoro, nitro, and hydrogen.

The compound of Formula X can be present in the phenolic composition inwidely varying ratios of Compound X to the polymeric composition but isgenerally present in a weight ratio of 1:30 to 1:2 and is preferablypresent in a weight ratio of 1:20 to 1:5. Examples of suitable compoundsof Formula X include among others: m-cresol, m-chlorophenol,m-nitrophenol, 3,5-xylenol, and phenol, i.e., hydroxy benzene. Phenol isthe most preferred compound of Formula X because of cost, availability,and reactivity. The phenolic polymers of Formula VI and Formula VIII areproduced according to the present invention by combining the reactantsin a two-step process described in Moss, U.S. Pat. No. 3,876,620.

In the broadest aspects of the present invention, any aldehyde can beemployed to produce useful phenolic polymers. Examples of suitablealdehydes include, among others, furfural, formaldehyde, benzaldehyde,and acetaldehyde. Formaldehyde is the preferred aldehyde. Formaldehydecan be employed in widely varying forms such as the 37% aqueous solutionwidely known as formalin. However, it is generally necessary to removefrom the polymeric material the water introduced with the formalin.Formaldehyde is preferably employed in the form of paraformaldehydewhich contains much less water.

The cellular material of the present invention is formed by simplyreacting the alkylol group containing phenolic polymer of Formula VI orFormula VIII and the compound of Formula X under conditions such that acellular product will result. As is well known in the phenolic foam art,the reaction can be conducted in the presence of a foaming catalyst, ablowing agent, and a surfactant. The reaction can be performed betweentemperatures of 10°-50° C., preferably 15°-25° C., and conveniently atatmospheric pressure. The cellular materials of the present inventiongenerally have a thermal conductivity, k-factor value of from 0.1 to0.3, and preferably from 0.1 to 0.2 Btu/hr°F.-sq. ft. per inch asmeasured at 24° C. The k-factor value is measured on a Model 88 machinesupplied by the ANACON Company. The friability of the cellular materialis 20% or less. Friability is the propensity of the foam to breakexpressed in percent weight loss. This is determined by the ASTM C-421friability test conducted for 10 minutes.

In the broadest aspeots of the present invention, any catalyst whichwill enhance the cross-linking and foaming reaction can be employed inthe present invention. However, the preferred foaming catalysts arearomatic sulfonic acids, examples of which include, among others,benzene sulfonic acid, toluene sulfonic acid, xylene sulfonic acid, andphenol sulfonic acid. Phosphoric acid can also be employed either aloneor in admixture with the sulfonic acids. The preferred sulfonic acid isa mixture of equal parts by weight of toluene sulfonic acid and xylenesulfonic acid, as described in Mausner et al. U.S. Pat. No. 3,458,449.Another foaming catalyst which has been found to give excellent resultsis a blend of toluene sulfonic acid, phosphoric acid, and water in aweight ratio of 35-50:50-35:15.

The catalyst is generally present in the minimum amount that will givethe desired cream times of 10 to 120 seconds and firm times of 40 to 600seconds to the reacting mixture. The catalyst, however, generallycomprises from 0.5 to 20, and preferably comprises from 1.0 to 15,weight percent, based on the weight of the cellular material.

Any blowing agent characteristically employed in similar prior artproducts, such as is described in Moss et al., U.S. Pat. No. 3,968,300,can be employed in the composition of the present invention. In general,these blowing agents are liquids having an atmospheric pressure boilingpoint between minus 50° and 100° C. and preferably between zero and 50°C. The preferred liquids are hydrocarbons or halohydrocarbons. Examplesof suitable blowing agents include, among others, chlorinated andfluorinated hydrocarbons such as trichlorofluoromethane, CCl₂ FCClF₂,CCl₂ FCF₃, diethylether, isopropyl ether, n-pentane, cyclopentane, and2-methylbutane. Combinations of trichlorofluoromethane plus1,1,2-trichloro-, 1,2,2-trifluoroethane, are the preferred blowingagents. The blowing agents are employed in an amount sufficient to givethe resultant foam the desired bulk density which is generally between0.5 and 10, and preferably between 1 and 5 pounds per cubic foot. Theblowing agent generally comprises from 1 to 30, and preferably comprisesfrom 5 to 20 weight percent of the composition. When the blowing agenthas a boiling point at or below ambient, it is maintained under pressureuntil mixed with the other components. Alternatively, it can bemaintained at subambient temperatures until mixed with the othercomponents.

The cellular phenolic product formed by using the metal catalyzedsurfactant of the invention has a uniform, fine-celled structure.Uniformity of cells is determined by visual and microscopic examination.This property of producing a fine-celled foam is tested by mixing 2 to5% of the surfactant with the phenolic composition and producing a foamas described herein.

The average cell size diameter should ideally be less than 0.2 mm and ismore preferably less than 0.1 mm (ASTM D-2842). Fine-celled foams can bythe means set forth in the invention be rendered closed cells. Theblowing agent is then trapped in the cells. One means of expressing thecontainment in the cells of the blowing agent is by use of the k-factordrift value. Unfaced cellular materials containing fluorocarbon gas haveinitial k-factors in the vicinity of 0.1-0.2 at 24° C. This low valueincreases over a period of months or sometimes days. The change isexpressed as the k-factor drift. The k-factor is measured at a meantemperature of 24° C. The value is redetermined at various timeintervals up to about 1000 days. A material exhibiting fast k-drift willattain a k-factor (BTU/hr-°F.-ft² per inch thickness) of at least 0.2within 25 days. A slow k-drift material may require between 200 days andover two years to attain a 0.2 value. Any material which possesses ak-value under 0.2 will provide high thermal resistance. Obviously, thelonger this value or a lower value is maintained, the better theefficiency.

Ball, Hurd, and Walker have published a comprehensive discussion ofk-factor changes as a function of time. ("The Thermal Conductivity ofRigid Urethane Foams", J. Cellular Plastics, March/April, 1970, pp66-78). F. Norton ("Thermal Conductivity and Life of Polymer Foams", J.Cellular Plastics, January, 1967, pp 23-37) has shown that diffusion offluorocarbon gases out of unfaced foam and infusion of air into the foamcauses an increase in k-factor. A slow k-drift foam is defined as onethat attains a k-factor at 24° C. of 0.15-0.17 after 200-400 days andthen remains below 0.2 k-factor for 5-10 years. Eventually allfluorocarbon diffuses from the foam to leave a closed cell materialwhich contains only air in the cells.

The k-factor for the closed cell foam containing only air falls in therange of 0.22-0.26 BTU/hr-°F.-ft² per inch thickness at 24° C. for the2-3 lbs/ft³ density range. Therefore, if a foam exhibits greater than0.2 k-factor after a short period of time (less than 25 days), thensubstantially all fluorocarbon has diffused from the foam and has beenreplaced by air. On the other hand, if the k-factor remains below 0.2for at least 100 days, then a substantial amount of fluorocarbon gasremains in the closed cells of the foam in spite of infusion of air.

It has been found that use of the metal catalyzed surfactant of theinvention results in a fine-celled phenolic foam with high closed cellcontent, a low initial k-factor and a low k drift value.

Referring now to the drawings, and in particular to FIG. I, there isshown a laminated building panel 10 of the invention. The building panel10 comprises a single facing sheet 11 having thereon a cellular material12 of the present invention. FIG. II shows a building panel 20 havingtwo facing sheets 21 and 22 on either side of a cellular material 23.

Any facing sheet previously employed to produce building panels can beemployed in the present invention. Examples of suitable facing sheetsinclude, among others, those of kraft paper, aluminum, and asphaltimpregnated felts, as well as laminates of two or more of the above.

The foam materials of the invention can also be used, with or without afacer(s), for pipe insulation.

The invention is further illustrated by the following examples in whichall parts and percentages are by weight unless otherwise indicated.These non-limiting examples are illustrative of certain embodimentsdesigned to teach those skilled in the art how to practice the inventionand to represent the best mode contemplated for carrying out theinvention.

EXAMPLE 1

This example illustrates the preparation of metal catalyzed surfactantsin accordance with the present invention.

0.33 g of ferrocene was added to 200 g (0.036 mole) of ethoxylatedpropoxylated ethylene diamine (Tetronic 704) in a 500 ml resin kettleequipped with an overhead stirrer. A nitrogen stream was providedthrough the resin kettle. A solution containing 6 g (0.032 mole) oftert.-butyl perbenzoate (TBP) dissolved in 34 g (0.145 mole) of dibutylmaleate (DBM) was added slowly over two hours to the polyol from anaddition funnel. At the same time, 16 g (0.145 mole) ofN-vinyl-2-pyrrolidinone (NVP) was slowly added to the polyol from asecond addition funnel. During the addition, the reaction mixture wasmaintained at 90° C. After the addition, the temperature of the reactionmixture was increased to 140° C. for one hour and then allowed to coolto room temperature. Acetic anhydride (17 g, 0.16 mole) was next addedover a 20 minute period to the reaction mixture. The mixture was heatedto 100° C. for one hour and then cooled to room temperature to produce asurfactant of the present invention. (Surfactant No. 1 of Table Ibelow). (The acetic anhydride caps the hydroxyl end groups of the polyolwith acetate groups.)

The above alkoxylated diamine used in the preparation of the surfactantof the invention has a molecular weight of 5500, has a weight ratio ofethylene oxide to propylene oxide of 40:60, and is available from theBASF Wyandotte Corporation, Wyandotte, Mich., U.S.A., under thetradename "TETRONIC 704."

Surfactant Nos. 2-36 of Table I below were prepared in a similar manneremploying Tetronic 704, DBM and NVP in the same concentrations asutilized above and the initiators and metal catalysts listed in thetable in the concentrations designated therein. All surfactants of TableI were in the form of liquids. Surfactant Nos. 1-33 are illustrative ofthe present invention, while Surfactant Nos. 34-36 are comparativesurfactants illustrating the use of an azo initiator together with ametal catalyst of the invention. The azo initiator is the sole initiatorin the production of Surfactant No. and is used in combination with aperoxidic initiator in the production of Surfactant Nos. 34 and 35.

                  TABLE I                                                         ______________________________________                                        Preparation of Metal Catalyzed Surfactants                                    Initiator(s)       Metal Salt(s)                                              Sur-              Concen-             Concen-                                 factant           tration             tration                                 No.   Type        (%).sup.a                                                                              Type       (%).sup.a                               ______________________________________                                        1     tert.-Butyl 2.4      Ferrocene  0.13                                          Perbenzoate                                                             2     tert.-Butyl "        "          "                                             Perbenzoate                                                             3.sup.b                                                                             tert.-Butyl 2.3      Ferrous Sulfate                                                                          0.2                                           Perbenzoate          Ferric Sulfate                                                                           "                                       4.sup.b                                                                             tert.-Butyl 0.6      Ferrous Sulfate                                                                          "                                             Perbenzoate          Ferric Chloride                                                                          "                                       5.sup.b                                                                             tert.-Butyl 1.2      Ferrous Sulfate                                                                          "                                             Perbenzoate          Ferric Sulfate                                                                           "                                       6.sup.b                                                                             tert.-Butyl 1.8      Ferrous Sulfate                                                                          "                                             Perbenzoate          Ferric Sulfate                                                                           "                                       7.sup.b                                                                             tert.-Butyl 2.4      Ferrous Sulfate                                                                          "                                             Perbenzoate          Ferric Sulfate                                                                           "                                       8     tert.-Butyl "        Manganese (II)                                                                           "                                             Perbenzoate          Acetylacetonate                                                               Manganese (III)                                                                          "                                                                  Acetylacetonate                                    9     tert.-Butyl "        Cobalt (II)                                                                              0.2                                           Perbenzoate          Benzoate                                                                      Cobalt (III)                                                                             0.26                                                               Acetylacetonate                                    10    tert.-Butyl "        Cuprous Acetate                                                                          0.09                                          Perbenzoate          Cupric     0.2                                                                Acetylacetonate                                    11    tert.-Butyl "        Cupric     0.2                                           Perbenzoate          Acetylacetonate                                    12    tert.-Butyl "        Vanadium (III)                                                                           0.2                                           Perbenzoate          Acetylacetonate                                                               Vanadium (IV)                                                                            0.2                                                                Oxide                                                                         Acetylacetonate                                    13    tert.-Butyl "        Ferrocene  0.13                                          Perbenzoate          Ferric     0.24                                                               Acetylacetonate                                    14    tert.-Butyl "        Ferric     0.24                                          Perbenzoate          Acetylacetonate                                    15    tert.-Butyl "        Ferrous    0.2                                           Perbenzoate          Acetylacetonate                                    16    tert.-Butyl "        Ferrocene  0.016                                         Perbenzoate                                                             17    tert.-Butyl "        Ferrocene  0.008                                         Perbenzoate                                                             18    tert.-Butyl "        "          0.004                                         Perbenzoate                                                             19    tert.-Butyl "        "          0.002                                         Perbenzoate                                                             20    tert.-Butyl "        "          0.00016                                       Perbenzoate                                                             21    tert.-Butyl "        "          0.00008                                       Perbenzoate                                                             22    tert.-Butyl "        "          0.26                                          Perbenzoate                                                             23    tert.-Butyl 4.8      "          "                                             Perbenzoate                                                             24    tert.-Butyl "        "          0.13                                          Perbenzoate                                                             25    tert.-Butyl 1.2      "          "                                             Hydroperoxide                                                           26    tert.-Butyl "        Ferrocene  0.13                                          Hydroperoxide        Ferric     0.2                                                                Acetylacetonate                                    27    Cumene       1.76    Ferrocene  0.13                                          Hydroperoxide                                                           28    Cumene      "        Ferrocene  0.13                                          Hydroperoxide        Ferric     0.2                                                                Acetylacetonate                                    29    Lauroyl      2.56    Ferrocene  0.13                                          Peroxide                                                                30    Lauroyl     "        Ferrocene  0.13                                          Peroxide             Ferric     0.2                                                                Acetylacetonate                                    31    Benzoyl     3.1      Ferrocene  0.13                                          Peroxide                                                                32    Di-tert.-    1.88    "          "                                             Butyl                                                                         Peroxide                                                                33    Dicumyl      3.44    "          "                                             Peroxide                                                                34    tert.-Butyl 2.4      "          "                                             Perbenzoate                                                                   Azobisiso-  0.4                                                               butyronitrile                                                           35    tert.-Butyl 0.2      Ferrocene  0.13                                          Perbenzoate                                                                   Azobisiso-  0.4                                                               butyronitrile                                                           36    Azobisisobutyro-                                                                          2.1      Ferrocene  0.13                                          nitrile                                                                 ______________________________________                                         .sup.a The initiator and metal salt concentrations are each based on the      total weight of the reaction mixture.                                         .sup.b In the preparation of Surfactant Nos. 3 to 7 a precipitate formed.     The precipitate was separated from the surfactants by filtration through      glass wool.                                                              

EXAMPLE 2

This example illustrates the synthesis of metal catalyzed surfactants ofthe invention utilizing "Pluronic" polyols (available from BASFWyandotte Corporation) as the polyoxyalkylene adduct.

A. Method of Preparation

A 500 ml resin kettle equipped with an overhead stirrer was charged witha mixture of 200 g of a Pluronic polyol (listed in Table II below) and0.33 g (0.0018 mole) of ferrocene. While stirring the mixture undernitrogen at a temperature of 90° C., 16 g (0.145 mole) ofN-vinyl-2-pyrrolidinone (NVP) and 34 g (0.145 mole) of dibutyl maleate(DBM) were added separately from two addition funnels over two hours. 6g (0.032 mole) of tert.-butyl perbenzoate (TBP) was dissolved in thedibutyl maleate prior to the addition. Following the addition, thetemperature was increased to 140° C. for one hour. The mixture was thencooled to room temperature and the appropriate amount of aceticanhydride (determined from the polyol's hydroxyl number) was added tocap the polyol. The temperature was next increased to 100° C. for onehour, after which the surfactant product was cooled to room temperature.By following this procedure, surfactant Nos. 37-50 of the invention wereprepared utilizing the Pluronic polyols presented in Table II.

B. Molecular Weight and Ethylene Oxide Content of Pluronics

The molecular weight and ethylene oxide content of the Pluronic polyolsutilized in the preparation of Surfactant Nos. 37-50 are shown in thefollowing Table II. For comparison, the molecular weight and ethyleneoxide content of the Tetronic 704 adduct employed in Example 1 are alsoshown in the Table.

                  TABLE II                                                        ______________________________________                                        MOLECULAR WEIGHT AND ETHYLENE OXIDE                                           CONTENT OF PLURONICS                                                          Surfactant                                                                         Physical Polyol      Molecular                                                                             Weight %                                    No.  Form     Utilized    Weight  Ethylene Oxide                              ______________________________________                                        37   liquid   Pluronic L35                                                                              1900    50                                          38   liquid   Pluronic L43                                                                              1850    30                                          39   liquid   Pluronic L44                                                                              2200    40                                          40   liquid   Pluronic L63                                                                              2650    30                                          41   liquid   Pluronic L64                                                                              2900    40                                          42   paste    Pluronic P65                                                                              3400    50                                          43   solid    Pluronic F68                                                                              8350    80                                          44   liquid   Pluronic L72                                                                              2750    20                                          45   paste    Pluronic P84                                                                              4200    40                                          46   paste    Pluronic P85                                                                              4600    50                                          47   solid    Pluronic F87                                                                              7700    70                                          48   liquid   Pluronic P103                                                                             4950    30                                          49   liquid   Pluronic L122                                                                             5000    20                                          50   liquid   Pluronic L123                                                                             5750    30                                          --   liquid   Tetronic 704                                                                              5500    40                                          ______________________________________                                    

The letters L, P, and F before the numbers in the designation of eachPluronic polyol of Table II represent the physical form of the polyol:liquid, paste or flaky solid. The last digit of the numbers representsthe approximate weight percent of ethylene oxide contained in the polyoldivided by 10.

EXAMPLE 3

This example illustrates the synthesis of a phenolic polymer of FormulaVI useful in the present invention employing a molar ratio of phenol toortho cresol of 4:1.

The following quantities of the following ingredients were combined asindicated.

    ______________________________________                                                              Amount                                                  Item   Ingredient           grams   moles                                     ______________________________________                                        A      o-cresol             6,901   63.9                                      B      paraformaldehyde (93.5% HCHO)                                                                      3,133   97.7                                      C      sodium hydroxide (50% NaOH)                                                                        215     2.69                                      D      phenol               24,025  255.5                                     E      paraformaldehyde     11,350  354.1                                     F      sodium hydroxide (50% NaOH)                                                                        215     2.69                                      G      glacial acetic acid  350     5.8                                       ______________________________________                                    

Items A and B were charged to a reaction vessel. Item C was added over aperiod of fifteen minutes, the temperature rose due to the exothermicreaction to 100° C. and was maintained at that level for 1.5 hours.Items D, E, and F are then added and the temperature maintained at 80°C. for 5 hours. Item G was then added and the contents of the reactionvessel are termed Resin C.

Resin C has a viscosity at 25° C. of 22,000 cps, a free phenol contentof 9%, and a free water content of 10.9%, a free formaldehyde content of1.1%, and a free o-cresol content of less than 0.1%.

EXAMPLE 4

This example illustrates the synthesis of foaming catalysts useful inthe present invention.

The following quantities of the following ingredients were combined asindicated to produce Catalyst A:

    ______________________________________                                                   Ingredients    Quantity                                            Item       Name           grams                                               ______________________________________                                        A          p-toluene sulfonic acid                                                                      333                                                 B          xylene sulfonic acids                                                                        333                                                 C          water          333                                                 ______________________________________                                    

Items A, B, and C were mixed. The resultant composition is termedCatalyst A.

The following quantities of the following ingredients were combined asindicated to produce Catalyst B:

    ______________________________________                                                     Ingredients                                                                             Quantity                                               Item         Name      grams                                                  ______________________________________                                        A            Ultra TX  667                                                    B            water     333                                                    ______________________________________                                    

Items A and B were mixed. The resultant composition is termed CatalystB. Ultra TX is a mixture of equal parts by weight of p-toluene sulfonicacid and xylene sulfonic acids available from the Witco ChemicalCompany.

EXAMPLE 5

This example illustrates the synthesis of foams based on 4:1phenol:o-cresol resoles of the present invention.

    ______________________________________                                        Item     Ingredient          grams                                            ______________________________________                                        A        Resin C of Example 3                                                                              300                                              B        CFCl.sub.3          22.5                                             C        CFCl.sub.2 CF.sub.2 Cl                                                                            22.5                                             D        Surfactant (see Table III below)                                                                  15                                               E        Catalyst B of Example 4                                                                           35                                               ______________________________________                                    

Items A through E were mixed in an open vessel for 15-20 seconds. Themixture was then poured into a square paper box twelve inches by twelveinches by five inches tall. A foaming reaction ensued. After a period of300-600 seconds the material was rigid. The box and contents were placedin an oven at 55° to 75° C. for a period of ten minutes to one hour.

The characteristics of the foams synthesized utilizing as surfactantvarous metal catalyzed surfactants of Example 1 and a surfactantprepared in accordance with U.S. Pat. No. 4,140,842 are shown in thefollowing Table III.

                  TABLE III                                                       ______________________________________                                        Metal Catalyzed Surfactants in Resin C Foams                                                    Foam Characteristics                                                                Cell                                                                          Struc-                                                Foam No.                                                                              Surfactant      ture*   k-factor/days                                 ______________________________________                                        1       No. 1 of Example 1                                                                            Fine    .122/1, .127/14                                                               .130/70, .132/200,                                                            .139/365                                      2       No. 3 of Example 1                                                                            Fine    .127/1                                        3       No. 4 of Example 1                                                                            Fine                                                  4       No. 5 of Example 1                                                                            Fine                                                  5       No. 6 of Example 1                                                                            Fine                                                  6       No. 7 of Example 1                                                                            Fine                                                  7       No. 8 of Example 1                                                                            Fine                                                  8       No. 9 of Example 1                                                                            Fine                                                  9       No. 34 of Example 1                                                                           Fine                                                  10      No. 35 of Example 1                                                                           Coarse                                                11      No. 36 of Example 1                                                                           Very                                                                          Coarse                                                12      Surfactant A** of                                                                             Coarse                                                        U.S. Pat. No. 4,140,842                                               ______________________________________                                         *The cell quality of the foams was determined by visual and microscopic       examination.                                                                  **This surfactant was prepared as in Examples 3 and 4 of U.S. Pat. No.        4,140,842.                                                               

The results of Table III indicate that high quality foams (Foam Nos. 1to 8 of the invention) are produced by employing surfactants which areprepared in the presence of a metal catalyst and a per-compound.However, when the surfactant is prepared in the presence of a metalcatalyst and an azo initiator, a very poor quality foam (Foam No. 11)results. The quality of the foam is improved somewhat by replacing aportion of the azo initiator by a per-compound but the resultant foam(Foam No. 10) is still unacceptable. Only when a high proportion of theazo initiator is replaced by a per-compound is an acceptable foam (FoamNo. 9) obtained. Table III also shows that an inferior foam (Foam No.12) results when the surfactant utilized is manufactured by the processof U.S. Pat. No. 4,140,842, without the benefit of any metal catalysis.

EXAMPLE 6

The procedure of Example 1 utilized in the preparation of Surfactant No.1 was repeated except that no metal catalyst was added to the reactionmixture. The viscous liquid surfactant obtained in this Example wasutilized in the procedure of Example 5 and a fine-celled foam wasproduced.

EXAMPLE 7

This example illustrates the synthesis of a phenolic polymer of FormulaVI useful in the present invention employing a molar ratio of phenol too-cresol of 2:1.

The following quantities of the following ingredients were combined asindicated.

    ______________________________________                                                              Amount                                                  Item    Ingredient       grams       moles                                    ______________________________________                                        A       o-cresol         10,580      98                                       B       paraformaldehyde (93.6%)                                                                       4,743       148                                      C       sodium hydroxide (50%)                                                                         295         3.69                                     D       phenol           18,428      196                                      E       paraformaldehyde 7,917       247                                      F       glacial acetic acid                                                                            225         3.75                                     ______________________________________                                    

Items A and B were charged to a reaction vessel. Item C was added over aperiod of fifteen minutes, the temperature rose to 100° C. due to anexothermic reaction and was maintained at that level for 1 hour. Items Dand E were then added and the temperature maintained at 80° C. for fourand one-half hours. Item F was then added and the contents of thereaction are termed Resin B.

Resin B has a viscosity at 25° C. of 31,500 cps, a free phenol contentof 8.5%, and a free water content of 10.5%, a free formaldehyde contentof 1.2%, and a free o-cresol content of less than 0.1%.

EXAMPLE 8

This example illustrates the synthesis of foams based on 2:1phenol:o-cresol resoles of the present invention. The followingquantities of the following ingredients were combined as indicatedbelow.

    ______________________________________                                        Item     Ingredient          grams                                            ______________________________________                                        A        Resin B of Example 7                                                                              300                                              B        CFCl.sub.3          22.5                                             C        CCl.sub.2 FCF.sub.2 Cl                                                                            22.5                                             D        Surfactant (See Table IV below)                                      E        Catalyst B of Example 4                                                                           40                                               ______________________________________                                    

Items A through E were mixed at 15° C. in an open vessel for 15 seconds.The mixture was then poured into a square paper box twelve inches bytwelve inches by five inches tall. A foaming reaction ensued. After aperiod of about 240-600 seconds the material was rigid. The box andcontents were placed in an oven at 55° to 75° C. for a period of tenminutes to one hour. Properties of the foams are shown in the followingTable IV.

                                      TABLE IV                                    __________________________________________________________________________    Metal Catalyzed Surfactants in Resin B Foams                                                  Phenolic Foam Properties                                                                   k-Factor                                         Surfactant.sup.1                                                                      Resin B.sup.2                                                                         Density,                                                                           Friability, %                                                                         Days                                             No.     Viscosity.sup.3, cps                                                                  pcf  wt. loss/10 min.                                                                      1  7  14 28                                      __________________________________________________________________________    41 of Example 2                                                                       18,500               .114                                                                             .126                                                                             .130                                                                             .136                                    "       31,000  2.5  12      .125                                                                             .120                                                                             .120                                                                             .123                                    "       "                    .121                                                                             .118                                                                             .120                                                                             .123                                    "       "                    .123                                                                             .118                                                                             .119                                                                             .118                                     1 of Example 1                                                                       22,000               .127                                                                             .131                                                                             .132                                                                             .134                                    "       50,000               .125                                                                             .126                                                                             .122                                                                             .128                                    "       "       2.8  10      .128                                                                             .13                                                                              .131                                                                             .133                                    __________________________________________________________________________     .sup.1 5 phr of surfactant, based on the Resin B polymer weight, were use     in each foam.                                                                 .sup.2 Each Resin B of Table IV was prepared according to the procedure o     Example 7.                                                                    .sup.3 Brookfield viscosities at 25° C.                           

The Table IV results show that the metal catalyzed surfactants of theinvention prepared from both Pluronic L64 (Surfactant No. 41) andTetronic 704 (Surfactant No. 1) contribute to the production of phenolicfoams having similarly low initial k-factors, low k-factor drift ratesand low friabilities. However, the Pluronic-based surfactant has anadvantage over the Tetronic-based one in large scale phenolic foamproduction wherein there is utilized a so-called "B-component"consisting of a solution of surfactant (5 phr) with a blowing agentcombination of freon 11 (2.5 phr) and freon 113 (7.5 phr). While thePluronic surfactant B-component mixture was a clear, stable solution, acombination of the Tetronic 704 surfactant with the blowing agentsresulted in the formation of a cloudy precipitate.

EXAMPLE 9

By essentially following the foam production method of Example 8 andsubstituting the following surfactants of Table II for Surfactant Nos. 1and 41 of Table IV, a series of phenolic foams based on 2:1phenol:o-cresol resoles were produced. Properties of the foams are shownin the following Table V.

                                      TABLE V                                     __________________________________________________________________________    Metal Catalyzed Surfactants in Resin B Foams                                                Phenolic Foam Properties                                                           k-Factor                                                   Surfactant.sup.1                                                                    Resin B.sup.2                                                                         Density,                                                                           Friability, %                                                                         Days                                               No.   Viscosity.sup.3, cps                                                                  pcf  wt. loss/10 min.                                                                      1  7  14 28                                        __________________________________________________________________________    37    <40,000 2.15 12      .146                                                                             .149                                                                             .159                                                                             .173                                                                 .136                                                                             .146                                            38    <40,000 2.00 14      .138                                                                             .148                                                                             .159                                                                             .170                                                                 .143                                                                             .248                                            39    31,000  2.30 11      .126                                                                             .117                                                                             .114                                                                             .118                                                                 .124                                                                             .116                                                                             .124                                                                             .119                                      40    31,000  2.84 12      .121                                                                             .116                                                                             .114                                                                             .113                                                                 .123                                                                             .119                                                                             .120                                                                             .129                                      42    31,000  2.20 23      .122                                                                             .116                                                                             .128                                                                             .134                                      43    31,000  2.40 10      .130                                                                             .138                                                                             .133                                                                             .117                                                                 .120                                                                             .119                                                                             .112                                         44    13,00   1.55 14      .170                                                                          .225                                               45    31,000  2.70 11      .125                                                                             .118                                                                             .119                                                                             .118                                                                 .126                                                                             .117                                                                             .116                                                                             .116                                      46    31,000  2.20 21      .123                                                                             .120                                                                             .124                                                                             .143                                      47    31,000  2.27 18      .123                                                                             .127                                                                             .113                                                                             .116                                                                 .118                                                                             .119                                                                             .116                                                                             .121                                      49     9,000  1.75 15      .137                                                                             .214                                                                       .139                                                                             .179                                                                             .198                                         50    <40,000 2.27 10      .124                                                                             .120                                                                             .121                                                                             .123                                      __________________________________________________________________________     .sup.1 5 phr of surfactant, based on the Resin B polymer weight, were use     in each foam.                                                                 .sup.2 Each Resin B of Table V was prepared according to the procedure of     Example 7.                                                                    .sup.3 Brookfield viscosities at 25° C.                           

As the data in Tables II and V show, metal catalyzed surfactants of theinvention prepared from Pluronic polyols having an ethylene oxidecontent ranging from 30 to 80 weight % contributed to the production ofgood phenolic foams. All of these surfactants gave fine-celled, lowk-factor Resin B foams. The two surfactants of Table V prepared fromPluronics containing 20 weight percent ethylene oxide (nos. 44 and 49)also gave fine-celled Resin B foams, but the foams displayed highinitial k-factors. The high k-factor drift rates of the foams made withsurfactants based on Pluronic L43 (MW-1850) and Pluronic L35 (MW-1900),i.e., Surfactants Nos. 38 and 37, respectively, point to thedesirability of preparing the cell stabilizers of the invention frompolyols with a molecular weight of at least ca. 2000, as e.g.,Surfactant No. 39 (polyol MW-2200), which gave fine-celled, low k-factorResin B foams with low drift rates.

EXAMPLE 10

This example illustrates the solvent extraction of metal catalyzedsurfactants of the present invention and the utilization of the extractas surfactant in the synthesis of a foam based on a 2:1 phenol:o:cresolresole of the invention.

A. Solvent Extraction

Surfactant Nos. 1, 2, 19, and 34 of Example 1 and the surfactant ofExample 6 were each separately extracted with hexane as follows:

A 50 or 100 g sample of the surfactant was placed into a 1 literErlenmeyer flask. Approximately 800 ml of hexane was added and themixture was boiled, while being stirred, for 30 minutes. The mixture wasallowed to stand at room temperature for 10 minutes and the hexane wasdecanted from an insoluble residue. The decanted hexane was evaporatedin a vacuum leaving an extracted material. The process was repeatedthree times, yielding an insoluble residue as the major component and aviscous liquid extract from the decanted hexane as the minor component.The percent of each surfactant (minor component) which was extracted andthe properties of phenolic foams which were synthesized utilizing theseextracts as surfactant are shown in Table VI below.

B. Phenolic Foam Preparation

By essentially following the foam production method of Example 8 andsubstituting the following surfactants of Table VI for Surfactant Nos. 1and 41 of Table IV, phenolic foams were produced having the propertiesshown in Table VI.

                  TABLE VI                                                        ______________________________________                                        Extracts of Surfactants in Resin B.sup.1 Foams                                                 Phenolic Foam Properties                                              Percent                     Friability                               Surfactant                                                                             Ex-      Cell     k-factor/ % wt. loss,                              Extracted.sup.2                                                                        tracted  Structure                                                                              Days      10 min.                                  ______________________________________                                        No. 1    14       Fine     .125/1, .151/7,                                                                         17                                       (Table I)                  .156/14                                            No. 2    15       Fine     .123/1, .131/14,                                                                        21                                       (Table I)                  .137/7, .142/21                                    Surfactant                                                                             13       Coarse             50                                       of Example 6                                                                  No. 19   14       Coarse             65                                       (Table I)                                                                     No. 34   17       Very                                                        (Table I)         Coarse                                                      ______________________________________                                         .sup.1 The Resin B polymer used in the phenolic foam preparations had a       Brookfield viscosity at 25° C. of 20,000 (cps).                        .sup.2 5 phr of surfactant, based on the Resin B polymer weight, were use     in each foam.                                                            

The Table VI results indicate that the extracted surfactant's ability tostabilize phenolic foams can be improved by preparing the surfactant inthe presence of (1) a ferrocene amount greater than 0.002 g/100 gpolyol, (2) a tert.-butyl perbenzoate-ferrocene system rather thantert.-butyl perbenzoate alone, and (3) a tert.-butylperbenzoate-ferrocene system uncombined with any azobisisobutyronitrile.

Whereas the present invention has been described with respect tospecific embodiments thereof, it should be understood that the inventionis not limited thereto, as many modifications thereof may be made. Itis, therefore, contemplated to cover by the present application any andall such modifications as fall within the true spirit and scope of theappended claims.

I claim:
 1. In the process of preparing a cellular foam from phenolaldehyde resin forming reactants and a blowing agent, the improvementwhich comprises utilizing as the surfactant the product of a freeradical addition polymerization of a cyclic nitrogenous vinyl monomerand an esterified unsaturated dibasic acid in the presence of (a) apolyoxyalkylene adduct having the formula

    H--polyoxyalkylene chain).sub.t R,

wherein R is an organic or inorganic radical and t is the number ofpolyoxyalkylene chains reacted onto R, (b) an organic or inorganicper-compound, and (c) a metal catalyst selected from the groupconsisting of ferrocene, acetylferrocene, benzoylferrocene, cobaltocene,1,1'-diacetylferrocene, 1,1'-ferrocene-bis(diphenyl-phosphine),nickelocene, hafnocene dichloride, ferrocenecarboxaldehyde, mixtures ofsaid ferrocene compounds and other transition metal compounds containinga metal having an atomic number of 21 to 30, and a mixture of compoundsselected from the group consisting of iron (II) sulfate and iron (III)sulfate, iron (II) sulfate and iron (III) chloride, manganese (II)acetylacetonate and manganese (III) acetylacetonate, cobalt (II)benzoate and cobalt (III) acetylacetonate, copper (I) acetate and copper(II) acetylacetonate, and vanadium (III) acetylacetonate and vanadium(IV) oxide acetylacetonate, said polyoxyalkylene adduct optionally beingtreated either before or after said polymerization with a capping agentcapable of reacting with the hydroxyl groups of said adduct to reducethe hydroxyl number of said adduct to less than 50, and the majorcomponent of said surfactant comprising the product formed from thereaction of said cyclic nitrogenous vinyl monomer and unsaturateddiester onto said polyoxyalkylene adduct.
 2. The process of claim 1wherein the cyclic nitrogenous vinyl monomer has the formula ##STR11##wherein n is 3, 4, or 5, and the esterified unsaturated dibasic acidcontains 4 or 5 carbon atoms in the acid portion.
 3. The foam materialof claim 2 wherein the esterified unsaturated dibasic acid has theformula

    C.sub.u H.sub.2u-2 (CO.sub.2 C.sub.v H.sub.2v+1).sub.2,

wherein u is 2 or 3 and y is an integer from 3 to
 18. 4. The foammaterial of claim 3 wherein the esterified unsaturated dibasic acid is amember selected from the group consisting of dibutyl fumarate, dibutylmaleate, dihexyl fumarate, diamyl methylenemalonate, dipropyl itaconate,and dibutyl itaconate.
 5. The foam material of claim 4 wherein thecyclic nitrogenous vinyl monomer is N-vinyl-2-pyrrolidinone and theesterified unsaturated dibasic acid is dibutyl maleate.
 6. The processof claim 1 wherein the per-compound is a member selected from the groupconsisting of an organic peroxide and an organic hydroperoxide.
 7. Theprocess of claim 1 wherein the per-compound is a member selected fromthe group consisitng of tert.-butyl perbenzoate, tert.-butylhydroperoxide, cumene hydroperoxide, lauroyl peroxide, benzoyl peroxide,di-tert.-butyl peroxide and dicumyl peroxide.
 8. The process of claim 1wherein the metal catalyst is a mixture of compounds selected from thegroup consisting of iron (II) sulfate and iron (III) sulfate; iron (II)sulfate and iron (III) chloride; manganese (II) acetylacetonate andmanganese (III) acetylacetonate; cobalt (II) benzoate and cobalt (III)acetylacetonate; copper (I) acetate and copper (II) acetylacetanate; andvanadium (III) acetylacetonate and vanadium (IV) oxide acetylacetonate.9. The process of claim 1 wherein the metal catalyst is a memberselected from the group consisting of ferrocene, acetylferrocene,benzoylferrocene, cobaltocene, 1,1'-diacetylferrocene,1,1'-ferrocenebis-(diphenyl-phosphine), nickelocene, hafnocenedichloride, and ferrocenecarboxaldehyde.
 10. The process of claim 1wherein the metal catalyst is ferrocene.
 11. The process of claim 10wherein the per-compound is tert.-butyl perbenzoate.
 12. The process ofclaim 1 wherein(a) the cyclic nitrogenous vinyl monomer isN-vinyl-2-pyrrolidinone, (b) the esterified unsaturated dibasic acid isdibutyl maleate, (c) the polyoxyalkylene adduct is a capped alkoxylatedamine having the formula: ##STR12## wherein R¹ is independently analkoxylated chain having the formula: ##STR13## s is an integer from 2to 10 inclusive and the ratio p:q is from 10:90 to 90:10, the molecularweight of said alkoxylated amine being from about 1500 to 6000, (d) theper-compound is a member selected from the group consisting oftert.-butyl perbenzoate, tert.-butyl hydroperoxide, cumenehydroperoxide, lauroyl peroxide, benzoyl peroxide, di-tert.-butylperoxide and dicumyl peroxide, and (e) the metal catalyst is a memberselected from the group consisting of copper (II) acetylacetonate, iron(II) acetylacetonate, iron (III) acetylacetonate, ferrocene, andmixtures of metal catalysts selected from the group consisting of iron(II) sulfate and iron (III) sulfate; iron (II) sulfate and iron (III)chloride; manganese (II) acetylacetonate and manganese (III)acetylacetonate; cobalt (II) benzoate and cobalt (III) acetylacetonate;copper (I) acetate and copper (II) acetylacetonate; and vanadium (III)acetylacetonate and vanadium (IV) oxide acetylacetonate.
 13. The processof claim 12 wherein the per-compound is tert.-butyl perbenzoate and themetal catalyst is ferrocene.
 14. The process of claim 1 wherein(a) thecyclic nitrogenous vinyl monomer is N-vinyl-2-pyrrolidinone, (b) theesterified unsaturated dibasic acid is dibutyl maleate, (c) thepolyoxyalkylene adduct is a capped linear block copolymer of ethyleneoxide and propylene oxide, the molecular weight of said block copolymerbeing above about 2000 and the ethylene oxide content being from about30 to 80 weight percent, (d) the per-compound is a member selected fromthe group consisting of tert.-butyl perbenzoate, tert,-butylhydroperoxide, cumene hydroperoxide, lauroyl peroxide, benzoyl peroxide,di-tert.-butyl peroxide and dicumyl peroxide, and (e) the metal catalystis a member selected from the group consisting of copper (II)acetylacetonate, iron (II) acetylacetonate, iron (III) acetylacetonate,ferrocene, and mixtures of metal catalysts selected from the groupconsisting of iron (II) sulfate and iron (III) sulfate; iron (II)sulfate and iron (III) chloride; manganese (II) acetylacetonate andmanganese (III) acetylacetonate; cobalt (II) benzoate and cobalt (III)acetylacetonate; copper (I) acetate and copper (II) acetylacetonate; andvanadium (III) acetylacetonate and vanadium (IV) oxide acetylacetonate.15. The process of claim 14 wherein the per-compound is tert.-butylperbenzoate and the metal catalyst is ferrocene.
 16. The process ofclaim 1 wherein the cyclic nitrogenous vinyl monomer and esterifiedunsaturated dibasic acid together comprise between about 5 and 40 weightpercent of the polymerization reaction mixture, the per-compoundcomprises from about 2 to 30 weight percent, based on the moles ofcyclic nitrogenous vinyl monomer and esterified unsaturated dibasicacid, and the metal catalyst comprises from about 0.001 to 0.06 gramsper gram of per-compound.
 17. The process of claim 16 wherein theN-vinyl-2-pyrrolidinone and dibutyl maleate together comprise about 20weight percent of the polymerization reaction mixture and the molarratio of N-vinyl-2-pyrrolidinone to dibutyl maleate is about 1:1. 18.The process of claim 1 wherein the phenolaldehyde resin foam formingreactants comprise phenol and an ortho-cresolphenol block copolymer.